Rationale and Objectives: Approximately 5,800 infants and toddlers with developmental disabilities (e.g., cerebral palsy, Down syndrome, complex chronic conditions) and delays access Early Intervention Colorado (EI-CO) annually. Primary goals of EI-CO is to help children optimally function at home and in the community in order to increase early skill acquisition and minimize future rehabilitation and special education service use, but the effects of EI-CO are poorly understood. This proposal addresses this need by 1) examining disparities in EI-CO service use (Aim 1) and 2) estimating the impact of EI-CO service use on EI outcomes (Aim 2). Methods: Secondary analyses of existing EI-CO data from a major EI-CO program between 2008-2013 (n=3,500) and primary data collection of enrolled families (n=832) are used. Primary dependent variables are 1) EI service use (Aim 1) and 2) EI outcomes (Aim 2). EI service use will be measured from program billing data and dosage of EI service use will be calculated based upon service frequency and duration. EI outcomes will be measured from online questionnaires addressing functional task performance (e.g., mobility) and activity participation (e.g., personal care management). Econometric models will be used to estimate each outcome conditional on child and family characteristics and, for functional outcomes, service use, and perceived environmental barriers. Project Impact and Relevance to NCMRR: There is critical need for robust research evidence about the adequacy of EI services relative to functional outcomes to improve EI service delivery. However, knowledge gaps about EI service use and outcomes have posed significant barriers to building and translating this knowledge. Project results will yield important new knowledge about disparities in EI-CO service use and how disparities in service use contribute to variability in functional outcomes. These deliverables will improve our chances of successfully competing for NIH R01 funds to conduct a scale-up multi-site EI-CO outcomes study.